Linear operation type electric part

ABSTRACT

The present invention provides a linear operation type electric part in which a spring member for restoring the movement of a movable member and a spring member for preventing the backlash of the movable member are formed of the same kind of coil spring, thereby reducing the number of part used therefor, and enabling lower cost and increased productivity, and in which a movable member can be moved smoothly. The linear operation type electric part of the present invention includes the spring member, composed of the spring member for restoring the movable member from its movement and the spring member for preventing the movable member from backlash, both formed of the same type of coil springs. Therefore, it is possible to provide a linear operation type electric part which, when compared to conventional counterparts, requires fewer parts, thus enabling lower price and increased productivity. Moreover, in the present invention, the spring member does not slide along the case unlike in conventional counterparts, where the flat spring slides along the case. Therefore, it is possible to obtain a smooth movement of the movable member.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a linear operation type electric part which is provided in an automobile having an engine mounted therein, and which may be preferably used for a sensor for controlling a mixture ratio of fuel and air, a sensor for controlling the amount of exhaust gas to be recycled, and the like.

[0003] 2. Description Of The Related Art

[0004] Referring to FIGS. 11 to 13, a conventional linear operation type electric part of this kind will be described. A box case 31 includes a housing 31 a with an opened rear portion, a hole 31 b provided in the front portion so as to be in communication with the housing 31 a, and a pair of guide grooves 31 c provided in the front-to-back direction within the housing 31 a.

[0005] Moreover, an insulation substrate 33 having a resistive element 32 provided thereon is attached to the bottom of the housing 31 a. Inside of the housing 31 a is hermetically sealed by a sealing part 34 which closes the opened rear portion of the housing 31 a.

[0006] A movable member 35 having a pair of shoulder parts 35 a is movably accommodated in the housing 31 a, with the pair of shoulder parts 35 a being placed in the housing 31 a placed on the guide grooves 31 c. On the lower part of the movable member 35 is attached, a sliding member 36 which slides against the resistive element 32. Moreover, a flat spring 37 as shown in FIG. 13 is provided on an upper part of the movable member 35. The flat spring 37 presses down the movable member 35 so that the lower part of the movable member 35 is elastically abuts with the case 31 to prevent backlash along the vertical direction A. At the same time, the flat spring 37 prevents backlash along the width direction B.

[0007] A coil spring 38 for restoring movable member 35 from its movement is placed in the housing 31 a so as to be between the movable member 35 and the sealing part 34, so that the coil spring 38 presses the movable member 35 toward the front side of the case 31. An operation shaft 39 is inserted into a hole 31b such that linear movement of the operation shaft 39 along an axial direction causes the movable member 35 to linearly move.

[0008] Specifically, the spring force of the coil spring 38 acts in the same direction as the axial direction of the operation shaft 39 whereas the spring force of the flat spring 37 acts in the direction perpendicular to the axial direction.

[0009] Furthermore, the conventional linear operation type electric part operates as follows. First, as the operation shaft 39 is pressed along the axial direction, the movable member 35 moves toward the rear against the action of coil spring 38.

[0010] Thus, the sliding member 36 moves on the resistive element 32 together with the movable member 35 so as to produce a varying resistance value, and thus enabling position detection.

[0011] Moreover, during the movement of the movable member 35, the flat spring 37 moves together with the movable member 35 while sliding along the case 31. At the same time, the lower part of the movable member 35 moves while in slidable contact with the case 31.

[0012] When the pressure on the operation shaft 39 is released, the movable member 35 on which the sliding member 36 is attached and the operation shaft 39 are pushed back by the coil spring 38 so as to restore to the original state.

[0013] The conventional linear operation type electric part requires the flat spring 37 to prevent the backlash of the movable member 35 along the vertical and width directions in addition to the coil spring 38 for restoring the movable member 35 from its movement. In other words, there is a need for two kinds of spring parts, i.e., the coil spring 38 and the flat spring 37. The increased number of parts lead to an increased cost.

[0014] Moreover, placing the flat spring 37 inside the guide grooves 31 c requires cumbersome attachment work, and thus detracting from productivity. In addition, the flat spring 37 and the case 31 are in slidable contact with each other, so that the movable member 35 cannot move smoothly.

SUMMARY OF THE INVENTION

[0015] In view of above, it is an object of the present invention to provide a linear operation type electric part in which a spring member for restoring the movement of a movable member and a spring member for preventing the backlash of the movable member are formed of the same kind of coil spring, thereby reducing the number of part used therefor, and enabling lower cost and increased productivity, and in which a movable member can be moved smoothly.

[0016] As first means to solve the above-described problems, the structure according to the present invention comprises: an operation shaft linearly movable a along an axial direction; a movable member abutting with one end of the operation shaft, the movable member being disposed so as to be linearly movable by the operation shaft; a spring member for biasing the movable member so as to be restored from movement thereof; a case having a guide part for guiding the movable member during the movement thereof; and detection means disposed in a lower side of the movable member and operated by the movement of the movable member, wherein: the guide of the case comprises an upper guide sub-part and a lower guide sub-part for guiding sides of the movable member from above and below, respectively; the movable member comprises: a lower slide-contact part having the detection means on a lower side thereof and sliding in contact with the lower guide sub-part; and an upper slide-contact part located above and opposing to the lower slide-contact part, the upper slide-contact part sliding in contact with the upper guide sub-part; the upper and lower guide sub-parts and the upper and lower slide-contact parts form a restriction mechanism for restricting the movement of the movable member; the movable member receives from the spring member a turning moment for inclining a center line of the movable member in a width direction with respect to the axial direction, the center line extending along a front-to-back direction from a center of the movable member, thus rotating the movable member on a plane of the width direction; the rotation causes the upper and lower slide-contact part of the movable member to be pressed against and in contact with the upper and lower guide sub-parts of the case, respectively; the restriction mechanism restricts the movement of the movable member along the vertical and width directions so as to prevent a backlash of the movable member; and the movable member linearly moves while being inclined in the width direction with respect to the axial direction.

[0017] As second means to solve the problems, the restriction mechanism has a slanted surface on each of the upper and lower guide sub-parts or on each of the upper and lower slide-contact parts.

[0018] As third means to solve the problems, the restriction mechanism has a slanted surface on each of the upper guide sub-part and the upper slide-contact part or on each of the lower guide part and the lower slide-contact part.

[0019] As fourth means to solve the problems, the restriction mechanism comprises either a pair of the upper guide sub-part and the upper slide-contact part or on each of the lower guide sub-part and the lower slide-contact part formed so that the slanted surfaces are capable of abutting with each other while the other pair comprises an arc-shaped surface and a flat surface abutting with the arc-shaped surface.

[0020] As fifth means to solve the problems, the restriction mechanism comprises first and second restriction mechanisms provided on left and right sides along the width direction interposing the axial direction of the operation shaft.

[0021] As sixth means to solve the problems, one of the first and second restriction mechanisms is positioned near the operation shaft while the other of the first and second restriction mechanisms is positioned farther from the operation shaft than the one of the first and second restriction mechanisms.

[0022] As seventh means to solve the problems, the turning moment of the movable member is generated by the spring member comprising one coil spring.

[0023] As eighth means to solve the problem, the turning moment of the movable member is generated by the spring member comprising two coil springs disposed on left and right sides along the width direction interposing the axial direction of the operation shaft.

[0024] As ninth means to solve the problems, a pressure applied to the movable member by each of the two coil springs is differentiated by differentiating a distance between a position at which each coil spring abuts with the movable member and a position at which the coil spring abuts with the case.

[0025] As tenth means to solve the problems, the two coil springs are disposed at positions on a line extending perpendicularly to the axial direction of the operation shaft.

[0026] As eleventh means to solve the problems, the movable member is in elastic contact with the operation shaft due to an action of the spring member.

[0027] As twelfth means to solve the problems, the restriction mechanism is formed of a slanted surface on at least one of the upper guide sub-part and the upper sliding part, a flat surfaced on one of the lower guide sub-part and the lower sliding part, and a flat surface or at least one pair of convex portions in contact with the flat surface provided on the other of the lower guide sub-part and the lower sliding part.

[0028] As thirteenth means to solve the problems, the restriction mechanism is formed of a slanted surface on at least one of the lower guide sub-part and the lower sliding part, a flat surface on one of the upper guide sub-part and the upper sliding part, and a flat surface or at least one pair of convex portions in contact with the flat surface provided on the other of the upper guide sub-part and the upper sliding part.

[0029] As fourteenth means to solve the problems, the restriction mechanism comprises opposing slanted surfaces provided on the upper guide sub-part and on the upper slide-contact part, and opposing slanted surfaces on the lower guide sub-part and the lower slide-contact part, so that each pair of slanted surfaces are kept in elastic contact by the turning moment applied by the spring member.

[0030] As fifteenth means to solve the problems, the spring member comprises a first spring member for biasing the operation shaft so as to be restored from movement thereof, and a second spring member for biasing the movable member so as to be restored from movement thereof, wherein the second movable member is formed of one coil spring for pushing the movable member in a restoring direction at a position offset from the central axis.

[0031] As sixteenth means to solve the problems, prolonged arm parts, each extending toward outer ends along the width direction of the movable member and perpendicular to the axial direction, are provided on the operation shaft at an end contacting the movable member, each prolonged arm part being in contact with the first spring member, such that a pair of the first springs are provided at the outer ends along the width direction of the movable member so as to oppose each other.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032]FIG. 1 is a cross-sectional view of a linear operation type electric part according to one embodiment of the present invention viewed from the side;

[0033]FIG. 2 is a front view of a linear operation type electric part according to one embodiment of the present invention excluding a sealing member and an operation shaft;

[0034]FIG. 3 is a cross-sectional view of a main part of a linear operation type electric part according to one embodiment of the present invention as viewed from above;

[0035]FIG. 4 is an illustrative diagram showing a motion of a movable member of a linear operation type electric part according to one embodiment of the present invention;

[0036]FIG. 5 is a cross-sectional view of main parts sectioned along line 5-5 in FIG. 4;

[0037]FIG. 6 is a cross-sectional view of a linear operation type electric part according to another embodiment of the present invention as viewed from the side;

[0038]FIG. 7 is a front view of a linear operation type electric part according to another embodiment of the present invention excluding a sealing member and an operation shaft;

[0039]FIG. 8 is a cross-sectional view of a main part of a linear operation type electric part according to another embodiment of the present invention as viewed from above;

[0040]FIG. 9 is an illustrative diagram showing motion of a movable member of a linear operation type electric part according to another embodiment of the present invention;

[0041]FIG. 10 is a front view of main parts illustrating upper and lower guide sub-parts and upper and lower sliding parts of a linear operation type electric part according to another embodiment of the present invention;

[0042]FIG. 11 is a cross-sectional view of a conventional linear operation type electric part as viewed from the side;

[0043]FIG. 12 is a cross-sectional view of a conventional linear operation type electric part as viewed from above; and

[0044]FIG. 13 is a cross-sectional view of a flat spring of a conventional linear operation type electric part.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] With reference to the accompanying drawings, preferred embodiments of the linear operation type electric part according to the present invention will be described. FIG. 1 is a cross-sectional view of one embodiment of the linear operation type electric part according to the present invention as viewed from the side; FIG. 2 is a front view thereof excluding a sealing member and an operation shaft; FIG. 3 is a cross-sectional view of a main part thereof as viewed from above; FIG. 4 is an illustrative diagram showing a motion of a movable member of one embodiment of the linear operation type electric part according to the present invention; and FIG. 5 is a cross-sectional view of a main part sectioned along line 5-5 in FIG. 4.

[0046] Referring to FIGS. 1 to 5, one embodiment of the linear operation type electric part according to the present invention will be described. A molded case 1 formed of a synthetic resin includes: a hollow housing 1 a having an opening at one end thereof; a pair of concave shoulder parts 1 b which extend within the housing 1 a along a front-to-back direction; a pair of lower guide sub-parts 1 c which present arc-shaped convex arc faces extending within the housing 1 a along front-to-back direction; a pair of upper guide sub-parts 1 d which have slanted surface extending within the housing 1 a along front-to-back direction located above and opposing the lower guide sub-parts 1 c; a pair of round holding sections 1 e of different lengths, extending within the housing 1 a along front-to-back direction; and a tube-like part if projecting perpendicularly to the housing 1 a.

[0047] The lower guide sub-parts 1 c and the upper guide sub-parts id together form a guide part 1 g for a movable member 8 described later, and the guide part 1 g is formed in such a manner that a vertical distance interspace therein becomes smaller away from the central portion toward the outside along the width direction.

[0048] Moreover, as shown in FIG. 3, the pair of holding section 1 e have respectively different lengths due to different thicknesses of a back wall 1 h of the case 1 defining the holding section 1 e.

[0049] On an insulation substrate 3 having a plurality of metal terminals 2 attached thereon, a Hall IC 4 is attached so as to be electrically connected to the terminals 2. The insulation substrate 3 is inserted between the pair of the shoulder parts 1 b of the case 1 so as to be provided within the housing 1 a.

[0050] Each terminal 2 attached to the insulation substrate 3 is connected by soldering to one end of an L-shaped connector pin 5 embedded in the case 1.

[0051] A sealing member 6 made of a synthetic resin or the like includes an aperture 6 a provided in the center and a projecting strip portion 6 b provided in a rear portion of the outer periphery. The sealing member 6 is placed so as to cover the opening of the case 1 by crimping a part of the case 1 so that the projecting strip portion 6 b is received by the case 1. Therefore, the housing 1 a is hermetically sealed by the sealing member 6.

[0052] An operation shaft 7 includes a guard portion 7 a provided in the rear, and a convex portion 7 b provided at a rear end along an axial direction G. The operation shaft 7 is inserted through the aperture 6 a of the sealing member 6 from the rear to the front so that the guard portion 7 a is latched by the sealing member 6. Thus, the operation shaft 7 mounted to the sealing member 6 so as to be linearly movable.

[0053] The movable member 8, which is made of a molded synthetic resin, includes: a rectangular base 8 a positioned in the center extending along the front-to-back direction (which is the same as the axial direction G) and along the width direction which is perpendicular to the axial direction G; a pair of spring receiving parts 8 b extending from the base 8 a along the width direction having a cross-shaped end; a pair of front sliding parts 8 e located at the left and right sides along the width direction of a front end of the base 8 a, each composed of a lower sliding part 8 c having a flat surface (provided on the lower side) and an upper sliding part 8 d having a slanted surface (provided on the upper side); and a pair of rear sliding parts 8 f located at the left and right sides along the width direction of a rear end of the base 8 a, each composed of a lower sliding part 8 c having a flat surface (provided on the lower side) and an upper sliding part 8 d having a slanted surface (provided on the upper side).

[0054] A thickness along the vertical direction of the front and rear sliding parts 8 e and 8 f, respectively, each composed of the lower sliding part 8 c and the upper sliding part 8 d, becomes smaller away from the central portion toward the outer ends of the width direction.

[0055] Moreover, on a lower part of the movable member 8, a magnet 9 which is magnetized so as to have north and south poles along the axial direction G is attached. The movable member 8 having the magnet 9 attached thereto has a structure in which the lower and upper sliding parts 8 c and 8 d of the front and rear sliding parts 8 e and 8 f are inserted in the guide part 1 g, which is composed of lower and upper guide sub-parts 1 c and 1 d, with the magnet 9 facing a Hall IC 4. In the vicinity of the front sliding part 8 e, the lower and the upper slide-contact parts 8 c and 8 d, respectively, and the lower and the upper guide sub-parts 1 c and 1 d consist first restriction mechanisms 10 a. In the vicinity of the rear sliding part 8 f, the lower and the upper slide-contact parts 8 c and 8 d and the lower and the upper guide sub-parts 1 c and 1 d compose second restriction mechanisms 10 b.

[0056] On the lower side of the movable member 8 having the magnet 9 attached thereto, the lower slide-contact part 8 c abuts with the lower guide sub-part 1 c whereby its downward movement is restricted. Likewise, on the upper side of the movable member 8, the upper slide-contact part 8 d abuts with the upper guide sub-part 1 d whereby its upward movement is restricted.

[0057] When the movable member 8 is attached, the first restriction mechanisms 10 a are positioned closer to the operation shaft 7 whereas the second restriction mechanisms 10 b is positioned farther to the operation shaft 7 than the first restriction mechanisms 10 a. The magnet 9 and the Hall IC4 compose a detecting means K.

[0058] Spring members 11, composed of two springs, are each positioned within the holding section 1 e in the housing 1 a so that one end of each spring abuts with a back wall 1 h while another end of each spring abuts with the spring receiving part 8 b of the movable member 8.

[0059] Thus, two spring members 11 are positioned on right and left sides of the operation shaft 7 along the width direction interposing the axial direction G.

[0060] The two springs members 11 bias the movable member 8 forward so that the center of the movable member 8 is in elastic contact with a projection 7 b of the operation shaft 7. The two inserted spring members 11 are respectively accommodated in the two holding sections 1 e each having a different distance between a back wall 1 h and the spring receiving part 8 b, so that the two spring members 11 bias the movable member 8 with different forces. Consequently, as shown in FIG. 4, a turning moment M (rotary force) is generated in the movable member 8 so that the center line Z extending along the front-to-back direction (from a central portion of the movable member 8 along the width direction) becomes inclined with respect to the axial direction G. Therefore, the movable member 8 rotates around the operation shaft 7 on a plane extending along the width direction as its axis so that the center line Z becomes inclined with respect to the axial direction G of the operation shaft 7.

[0061] Moreover, when the turning moment M is generated in the movable member 8, the front sliding part 8 e, which is positioned on the left side of the movable member 8 is pushed into a space between the lower guide sub-part 1 c and the upper guide sub-part 1 d by rotating in a direction shown by an arrow Y as shown in FIG. 5. As a result, the lower slide-contact part 8 c defined by a flat surface of the movable member 8 is pressed until it abuts with the lower guide sub-part 1 c having an arc face, while the slanted surface of the upper guide sub-part 1 d and the slanted surface of the upper slide-contact part 8 d abut with each other.

[0062] Accordingly, the lower side of the movable member 8 is prevented from having a downward backlash by the lower guide sub-part 1 c, and the upper side of the movable member 8 is prevented from having an upward backlash by the upper guide sub-part 1 d. Furthermore, the movable member 8 is interposed between the lower guide sub-part 1 c and the upper guide sub-part 1 d so that backlash along the left-to-right direction (i.e., the width direction) is also prevented.

[0063] As described above, the first restriction mechanisms 10 a are composed of the lower part of the movable member 8, the upper slide-contact parts 8 c and 8 d, the lower part of the case 1, and the upper guide sub-parts 1 c and 1 d.

[0064] Moreover, when the turning moment M is generated in the movable member 8, the rear sliding part 8 f, which is positioned on right side of the movable member 8 is pressed into a space between the lower guide sub-part 1 c and the upper guide sub-part 1 d by rotating in a direction shown by an arrow X as shown in FIG. 5. As a result, the lower slide-contact part 8 c defined by the flat surface of the movable member 8 is pressed until it abuts with the lower guide sub-part 1 c having an arc face, with the slanted surface of the upper guide sub-part 1 d and the slanted surface of the upper slide-contact part 8 d abutting with each other.

[0065] Accordingly, the lower side of the movable member 8 is prevented from having a downward backlash by the lower guide sub-part 1 c, and the upper side of the movable member 8 is prevented from having an upward backlash by the upper guide sub-part 1 d. Furthermore, the movable member 8 is interposed between the lower guide sub-part 1 c and the upper guide sub-part 1 d so that backlash along the left-to-right direction (i.e., the width direction) is also prevented.

[0066] As described above, the second restriction mechanisms 10 b are composed of the lower part of the movable member 8, the upper slide-contact parts 8 c and 8 d, the lower part of the case 1, and the upper guide sub-parts 1 c and 1 d.

[0067] The first and second restriction mechanisms 10 a and 10 b, respectively, are provided in the left and right positions along the width direction interposing the axial direction G of the operation shaft 7. Two coil springs (spring members) 11, are disposed along one line W (refer to FIG. 2) perpendicular to the axial direction G of the operation shaft 7.

[0068] By disposing both spring members 11 along the line W, a good pressure balance is maintained when pressing the operation shaft 7.

[0069] As described above, when the turning moment M is generated in the movable member 8, the lower part of the front sliding part 8 e and the rear sliding part 8 f of the movable member 8 slide under elastic pressure while restricted by the flat surface of the lower guide sub-part 1 c. Accordingly, the downward movement of the movable member 8 is restricted by the lower guide sub-part 1 c. The upper part of the front sliding part 8 e and the rear sliding part 8 f of the movable member 8 slide under elastic pressure while restricted by the slanted surface of the upper guide sub-part 1 d. Accordingly, the upward movement of the movable member 8 is restricted by the upper guide sub-part 1 d. Therefore, the movable member 8 slides without experiencing a backlash along the vertical direction, so that the vertical distance between the Hall IC 4 and the magnet 9 is maintained at a fixed value.

[0070] If the vertical distance between the Hall IC 4 and the magnet 9 changed, an output value would change relative to a reference value. However, since the present invention ensures that a fixed vertical distance is maintained between the Hall IC 4 and the magnet 9, the movable member 8 can be held stably, and therefore, the output value does not vary even if vibration or the like is applied. Thus, it is possible to obtain an output value exhibiting excellent linearity as the magnet 9 moves.

[0071] Specifically, as shown in FIG. 5, in a cross section taken perpendicularly to the axial direction G, the lower part of the movable member 8, and the upper slide-contact parts 8 c and 8 d, abut with the lower part of the case 1, the upper guide sub-parts 1 c and 1 d, respectively, in the upper and lower positions, so that a backlash along the vertical direction is particularly prevented.

[0072] Furthermore, it is possible to move the movable member 8 while preventing a backlash along the horizontal direction (width direction). In addition, the rotary force applied to the movable member 8, which takes a value obtained by multiplying the spring constant by a difference between the spring deflections, can be kept constant at any sliding position of the movable member 8. Thus, a smooth movement can be realized.

[0073] Now, an operation of the linear operation type electric part of the present invention will be described. For example, when a pedal of an automobile is depressed, the operation shaft 7 moves against the force of the spring member 11 by way of an intervening member.

[0074] Along with the operation shaft 7, the movable member 8 moves linearly along the axial direction G while being guided by the first and second restriction mechanisms 10 a and 10 b.

[0075] The magnet 9 also moves and varies the magnetic field to the Hall IC 4. As a result, changing voltage values are detective by the detection means K, thus enabling position detection.

[0076] Moreover, when the pressure on the pedal is released, the movable member 8 is pushed back by the spring member 11, and the operation shaft 7 is also pushed back to the original state by the movable member 8.

[0077] Thus, the linear operation type electric part of the present invention may occur.

[0078] In the above-described embodiment, the detection means K has a structure that includes the magnet 9 and the Hall IC 4. Alternatively, the detection means K may have a structure including a potentiometer or the like composed of a resistive element and a slider.

[0079] Moreover, in the above-described embodiment, the first and second restriction mechanisms 10 a and 10 b, respectively, are provided on the upper side of the removable member 8 with the upper guide sub-part 1 d presenting a slanted surface and the upper slide-contact part 8 d presenting a slanted surface. Alternatively, they may have a structure composed of the lower guide sub-part 1 c and the lower slide-contact part 8 c each having a slanted surface on the lower side of the movable member 8.

[0080] Furthermore, in the above-described embodiment, the upper guide sub-part 1 d and the upper slide-contact part 8 d each presenting a slanted surface are provided for both of the case 1 and the movable member 8. Alternatively, the slanted surface may be provided to either the case 1 or the movable member 8.

[0081] In the above-described embodiment, the spring members 11 are composed of two coil springs each having equal spring force. By differentiating the distance between the case 1 and the movable member 8, compressing degree of the coil springs varies so as to generate the turning moment in the movable member 8. Alternatively, two coil springs each having equal spring force may be placed in different positions along the width direction from the axial direction G to generate the turning moment in the movable member 8, or two coil springs each having different spring force may be used to generate the turning moment in the movable member 8.

[0082] In the above-described embodiment, the turning moment is generated in the movable member 8 by two coil springs serving as the spring members 11. Alternatively, the spring members 11 may be composed of one coil spring or one twisted-coil spring, etc., which is an offset position from the axial direction G so as to generate the turning moment in the movable member 8.

[0083] Moreover, in the above-described embodiment, the turning moment M is generated in the movable member 8 by the operation shaft 7 abutting with the movable member 8 in a central portion thereof. However, the turning moment M may be generated in the movable member 8 by employing the operation shaft 7 so as to abut with the movable member 8 at a position offset from the central portion thereof.

[0084] In the above-described embodiment, the upper slide-contact parts 8 d presenting slanted surfaces are provided on the upper side of the movable member 8, and the upper guide sub-part having slanted surfaces is provided so as to oppose the case 1, so that when the turning moment M is generated, the movable member 8 is pressed toward the lower side. Alternatively, the slanted surface may be provided to the lower side of the movable member 8 so as to apply a pressure to the upper side of the movable member 8 by the slanted surface.

[0085] Moreover, the guide part 1 g in the form of a groove is formed in the case 1 in which the movable member 8 is inserted so that the movable member 8 freely moves along the front-to-back direction. Alternatively, a groove may be formed in the movable member 8 and a projection to be inserted in the groove may be provided on the case 1.

[0086] Moreover, in the above-described embodiment, a pair of the lower guide sub-parts 1 c are formed of arc-shaped convex, and the lower side of the front sliding part 8 e and the lower side of the rear slide part 8 f are of flat surfaces. Alternatively, the shapes of the parts may be reverse, or both may be flat surfaces.

[0087] Furthermore, in the above-described embodiment, the movable member 8 moves in a direction parallel to the axial direction G of the operation shaft 7 by the lower guide sub-parts 1 c. Alternatively, the lower guide sub-part 1 c may be slightly bent along the axial direction G to adapt to the output characteristics of the magnet 9 and the Hall IC 4. Likewise, the Hall IC 4 and the magnet 9 are placed parallel to each other by the pair of the lower guide sub-part 1 c in the above-described embodiment, but they may be placed slightly angled with each other by varying the height of the pair of the lower guide sub-parts 1 c.

[0088] In the above-described embodiment, the length of each of the pair of holding section 1 e is differentiated by varying the thickness of the back wall 1 h. Alternatively, compression degree of the spring member 11 may be varied by projecting one of the spring receiving part 8 b toward the back.

[0089] FIGS. 6 to 10 show the structure of the linear operation type electric part of another embodiment according to the present invention. FIG. 6 is a cross-sectional view of the linear operation type electric part according to the present invention viewed from the side, FIG. 7 is a front view thereof without a sealing member, FIG. 8 is a cross-sectional view showing a main part of the linear operation type electric part according to the present invention viewed from above, FIG. 9 is a diagram illustrating a movement of a movable member of the linear operation type electric part according to the present invention, and FIG. 10 is a front view illustrating a main parts, including the upper and lower guide sub-part and the upper and lower sliding part. The same part shown in FIG. 1 to 5 are denoted by the same reference numerals, and the description thereof is omitted.

[0090] Differences from the first embodiment illustrated with reference to FIGS. 1 to 5 are as follows: A part of a structure of the operation shaft and the movable member, a structure of spring members biasing the operation shaft and the movable member, and a structure of the upper and lower guide sub-parts and the upper and lower sliding parts.

[0091] Specifically, in the second embodiment, an operation shaft 57 is provided at the rear end of the shaft portion 57 a along the axial direction G. A convex portion 57 b abutting with a movable member 58 described later, and a pair of prolonged arm parts 57 c, each extending from proximity of the convex part 57 b toward outer ends along the width direction of the movable member 58 and perpendicular to the axial direction G, are formed. A first spring member 61 described later abuts with the prolonged arm parts 57 c. The first spring member 61 a is provided so as to be in contact with the prolonged arm parts 57 c, such that the first spring member 61 a are at the outer ends along the width direction of the movable member 58 so as to oppose each other.

[0092] The movable member 58 made of a molded synthetic resin is formed in a substantially rectangular shape. On both sides of the movable member 58 along the width direction, upper and lower sliding parts 58 d and 58 c, respectively, each composed of a slanted surface, are formed at the four corners (upper, lower, left and right) The front and rear sliding parts 58 e and 58 f composed of the front and rear slide-contact parts 58 d and 58 c are formed in such a manner that a vertical interspace therein becomes smaller away from the central portion toward the outside along the width direction.

[0093] In the movable member 58, a mounting hole 58 g having an opened lower portion is formed so as to receive the magnet 9 at a position offset from the center of the axis in one direction. The magnet 9, which is inserted in the mounting hole 58 g from above is fixed by a positioning plate 62 so that the lower side thereof faces the Hall IC 4. A spring housing hole 58 h is formed in a position opposite from the mounting hole 58 g which is offset from the central axis in another direction. By mounting a second spring member 61 b described later in the spring housing hole 58 h, the movable member 58 is pressed in a restoring direction at the position offset from the central axis.

[0094] A case 51, which is made of a molded synthetic resin, includes: a first housing part 51 a provided with an opening in the direction to which the operation shaft 57 is projected; and a second housing part 51 b formed to have an opening in the opposite direction from the first housing part 51 a. The first housing part 51 a includes: a guide part 51 g which accommodates the movable member 58 that can be linearly moved along the axial direction; and a circular-shape holding section 51 e which extends within the first housing part 51 a along the front-to-back direction on both sides of the guide part 51 g. Moreover, spring latching parts 51 i and 51 j for latching the first and second spring members 61 a and 61 b, respectively, are provided on an inner bottom portion of the first housing part 51 a.

[0095] The guide part 51 g composed of upper guide sub-part 51 d and a lower guide sub-part 51 c is formed at the four corners the movable member 58, the upper and lower sub-parts 51 d and 51 c sliding along an upper and lower slide-contact part 58 d and 58 c presenting slanted surfaces, respectively, while abutting therewith. The guide part 51 g is formed in such a manner that a vertical interspace therein becomes smaller away from the central portion toward the outside along the width direction. Moreover, a sealing member 6 is provided so as to cover the opening of the first housing part 51 a, so that the shaft 57 a of the operation shaft 57 is inserted through the aperture 6 a provided in the center of the sealing member 6, and thus, the operation shaft 57 is mounted so as to be linearly movable.

[0096] In the second housing 51 b, the insulation substrate 3 is provided by inserting thereto. On the insulation substrate 3, a plurality of metal terminals 2 and the Hall IC 4 which is electrically connected to the terminals 2 are attached. Each terminal 2 is connected by soldering to one end of an L-shaped connector pin 5 embedded in the case 51. The sealing member 56 is placed so as to cover the opening of the second housing part 51 b. The second housing part 51 b is place by crimping a part of the case 51 so as to be hermetically sealed.

[0097] The spring member 61 is composed of the first spring members 61 a and the second spring members 61 b, each composed of coil springs. The first spring members 61 a composed of two coil springs having the same specification are accommodated in the holding section 51 e of the case 51. One end thereof is latched by the spring latching part 51 i and another end by the prolonged arm part 57 c of the operation shaft 57, thereby the operation shaft 57 is biased forward so as to restore the movement along the axial direction.

[0098] Moreover, the second spring member 61 b composed of one coil spring is accommodated in the first housing part 51 a of the case 51. One end thereof is latched by the spring latching part 51 j and another end by the spring housing hole 58 h of the movable member 58. Accordingly, the center of the movable member 58 is in elastic contact with the convex portion 57 b of the operation shaft 57 by the movable member 58 being biased forward, and thus, restoring the movable member 58 from its movement along the axial direction.

[0099] In this case, the second spring member 61 b presses the movable member 58 in the restoring direction at the position offset from the central axis as shown in FIG. 9. Therefore, the turning moment M (rotary force) is generated in the movable member 58 by which the center line Z extending along the front-to-back direction (from the central portion of the movable member 58 along the width direction) becomes inclined with respect to the axial direction G. Accordingly, the movable member 58 rotates around the convex portion 57 b of the operation shaft 57 on a plane extending along the width direction as its axis of rotation while the center line z becomes inclined with respect to the axial direction G of the operation shaft 57. A load on the second spring member 61 b is set to be smaller than that of the first spring member 61 a.

[0100] When the turning moment M is generated in the movable member 58, the front sliding part 58 e positioned in the lift side of the movable member 58 is pushed into the space between the upper guide sub-part 51 d and the lower guide sub-part 51 c by rotating in the direction of arrow Y as shown in FIG. 10. Consequently, the upper guide sub-part 51 d having a slanted surface and the upper slide-contact part 58 d, and the lower guide sub-part 51 c and the lower slide-contact part 58 c respectively abut with each other while pressed along each slanted surface. Therefore, the movable member 58 is prevented from having a vertical backlash by the upper guide sub-part 51 d and the lower guide sub-part 51 c. In addition, the movable member 58 is interposed between the upper guide sub-part 51 d and the lower guide sub-part 51 c so that a horizontal (width direction) backlash is also prevented.

[0101] When the turning moment M is generated in the movable member 58, the rear sliding part 58 f positioned on the right side of the movable member 58 is pushed into the space between the upper guide sub-part 51 d and the lower guide sub-part 51 c by rotating in the direction of arrow X as shown in FIG. 10. Consequently, the upper guide sub-part 51 d having a slanted surface and the upper slide-contact part 58 d, and the lower guide sub-part 51 c and the lower slide-contact part 58 c are respectively in contact with each other while pressed along each slanted surface. Therefore, the movable member 58 is prevented from having a vertical backlash by the upper guide sub-part 51 d and the lower guide sub-part 51 c. In addition, the movable member 58 is interposed between the upper guide sub-part 51 d and the lower guide sub-part 51 c so that the horizontal (width direction) backlash is also prevented. Moreover, even if the movable member 58 and the guide part 51 g are abraded through sliding over long periods of use, the amount of abrasion would be substantially the same for the upper and lower sides. That is, the amount of rotation of the movable member 58 with respect to the case 51 would increase, but the distance between the magnet 9 and the Hall IC 4 would hardly be changed, so that the output value of the linear operation type electric part is unlikely to fluctuate.

[0102] The spring member 61 for restoring of the operation shaft 57 from its movement along the axial direction is composed of the first spring members 61 a i.e., two coil springs having the same specification. The first spring members 61 a abut with the pair of the prolonged arm parts 57 c extending toward outer ends along the width direction of the movable member 58 perpendicularly to the axial direction G, such that the first spring members 61 a are disposed on the outer ends of the movable member 58 along the width direction so as to oppose to each other. Thereby, the pressing forces for pressing the operation shaft 57 maintain a good balance. In addition, because the spring member 61 for restoring the movable member 58 from its movement is composed of a separate second spring member 61 b, restoring force applied to the contact portion of the operation shaft 57 and the movable member 58 may be dispersed, thus obtaining a more desirable operation touch.

[0103] To generate the turning moment M in the movable member 58, the second spring member 61 b is composed of a coil spring which is separately provided from the spring member having a coil spring for restoring the movement of the operation shaft 57. Therefore, it is possible to obtain a desirable and simple structure providing better mounting workability and low cost productivity.

[0104] With the above-described structure, when the turning moment M is generated in the movable member 58, the upper and lower portions of the front and rear sliding parts 58 e and 58 f of the movable member 58, respectively, slide under an elastic pressure while being interposed between the upper guide sub-parts 51 d and the lower guide sub-parts 51 c presenting the slanted surface. Thus, the movable member 58 slides without having a vertical backlash. Consequently, a fixed vertical distance is maintained between the Hall IC 4 and the magnet 9, so that the movable member 58 can be held stably, and therefore, the output value does not vary even if vibration or the like is applied. Thus, it is possible to obtain an output value exhibiting excellent linearity as the magnet 9 moves.

[0105] The linear operation type electric part of the present invention includes the spring member 11, composed of the spring member for restoring the movable member 8 from its movement and the spring member for preventing the movable member 8 from backlash, is formed of the same type of coil springs. Therefore, it is possible to provide a linear operation type electric part which, when compared to conventional counterparts, requires fewer parts, thus enabling lower price and increased productivity.

[0106] Moreover, in the present invention, the spring member 11 does not slide along the case 1 unlike in conventional counterparts, where the flat spring slides along the case. Therefore, it is possible to obtain a smooth movement of the movable member 8.

[0107] In the present invention, the movable member 8 receives from the spring members 11 the turning moment M for inclining the center line Z of the movable member 8 in a width direction with respect to the axial direction G, the center line Z extending along a front-to-back direction from a center of the movable member, thus rotating the movable member 8 on a plane of the width direction. The rotation causes the upper and lower slide-contact parts 8 d and 8 c of the movable member 8 to be pressed against and in contact with the upper and lower guide sub-parts 1 d and 1 c of the case 1, respectively. The restriction mechanism 10 a restricts the movement of the movable member 8 along the vertical and width directions so as to prevent a backlash of the movable member 8. The movable member 8 moves linearly while being inclined in the width direction with respect to the axial direction G. Accordingly, the movable member 8 is prevented from having a backlash along the width direction. In addition, in a cross section taken perpendicularly to the axial direction G, the lower part of the movable member 8, and the upper slide-contact parts 8 c and 8 d, abut with the lower part of the case 1, the upper guide sub-parts 1 c and 1 d, respectively, in the upper and lower positions, so that a backlash particularly along the vertical direction is prevented.

[0108] Because the restriction mechanisms 10 a have slanted surfaces on each of the upper and lower guide sub-parts 1 d and 1 c, respectively, or on each of the upper and lower slide-contact part 8 d and 8 c, respectively, the slanted surfaces can be provided as desired either in the movable member 8 and the case 1, thus enabling to obtain more flexibility.

[0109] Either a pair of the upper guide sub-parts 1 d and the upper slide-contact part 8 d or a pair of the lower guide sub-parts 1 c and the lower slide-contact part 8 c are formed so that the slanted surfaces are capable of abutting with each other while the other pair comprises restriction means having an arc-shaped surface and a flat surface abutting with the arc-shaped surface. Consequently, the arc-shaped surface and the flat surface abut linearly with each other so that it is possible to obtain smooth movement thereof and to enhance the positioning accuracy of the movable member 8 along the vertical direction.

[0110] The slanted surface 1 d or 8 d can be provided on either one of the movable member 8 and the case 1 or both thereof, and thus the slanted surfaces can be provided as desired either in the movable member 8 and the case 1, thus enabling to obtain more flexibility.

[0111] The restriction means are composed of the first and second restriction mechanisms 10 and 10 b provided on the left and right sides along the width direction interposing the axial direction G of the operation shaft 7, thereby enabling to guide the movable member 8 in two position (on the left and right sides). Consequently, it is possible to prevent the movable member 8 from having the vertical and horizontal (width direction) backlash even more securely.

[0112] One of the first and second restriction mechanisms 10 a and 10 b is positioned near the operation shaft 7 while the other of the first and second restriction mechanisms 10 a and 10 b are positioned farther from the operation shaft than the one of the first and second restriction mechanisms 10 a and 10 b. Thus, the movable member 8 is guided along the front-to-back direction with respect to the axial direction G, thus enabling to hold the movable member 8 securely.

[0113] The turning moment M of the movable member 8 is generated by the spring member 11 composed of one coil spring. Therefore, a fewer number of parts are required for the production of a linear operation type electric part of the present invention, thus enabling to lower price and increased productivity thereof.

[0114] The turning moment M of the movable member 8 is generated by the spring members 11 composed of two coil springs disposed on left and right sides along the width direction interposing the axial direction G of the operation shaft 7. Therefore, it is possible to provide a simple structure for generating the turning moment M in the movable member 8.

[0115] Moreover, a rotary force applied to the movable member 8 is a difference between the spring deflections applied to the movable member 8 by each coil spring, so that it is possible to make the rotary force smaller than a restoring force, thus realizing smooth movement of the movable member 8.

[0116] A pressure applied to the movable member 8 by each of the two coil springs is differentiated by differentiating a distance between a position at which each coil spring abuts with the movable member 8 and a position at which the coil spring abuts with the case 1. Consequently, coil springs each having the same spring force may be employed, thus enabling to obtain desirable productivity.

[0117] The two coil spring are disposed at positions on a line W extending perpendicularly to the axial direction G of the operation shaft 7. Thus, a good pressure balance is maintained when pressing the operation shaft 7, thus realizing a smooth movement of the movable member 8.

[0118] The movable member 8 is in elastic contact with the operation shaft 7 due to an action of the spring member 11. Therefore, it is possible to provide a linear operation type electric part without having a backlash between the operation shaft 7 and the movable member 8, thus obtaining accurate movement of the movable member 8.

[0119] The restriction mechanism is formed by a slanted surface on at least one of the upper guide sub-part 1 d and the upper sliding part 8 d, a flat surface on one of the lower guide sub-part 1 c and the lower sliding part 8 c, and a flat surface or at least one pair of convex portions in contact with the flat surface provided on the other of the lower guide sub-part 1 c and the lower sliding part 8 c. Therefore, when the turning moment is generated in the movable member 8 along the slanted surface, it moves until the flat surface on one of the lower guide sub-part 1 c and the lower sliding part 8 c or a pair of the flat surface and the convex portions abut with each other. Thus, it is possible to maintain the vertical interspace of the movable member 8, thereby providing a linear operation type electric part of the present invention having desirable output characteristics.

[0120] Moreover, the restriction mechanism is formed by a slanted surface on at least one of the lower guide sub-part 1 c and the lower sliding part 8 c, a flat surface on one of the upper guide sub-part 1 d and the upper sliding part 8 d, and a flat surface or at least one pair of convex portions in contact with the flat surface provided on the other of the upper guide sub-part 1 d and the upper sliding part 8 d. Therefore, when the turning moment is generated in the movable member 8 along the slanted surface, it moves until the flat surface on one of the lower guide sub-part 1 c and the lower sliding part 8 c or a pair of the flat surface and the convex portions abut with each other. Thus, it is possible to maintain the vertical interspace of the movable member 8, thereby providing a linear operation type electric part of the present invention having desirable output characteristics.

[0121] Furthermore, the restriction mechanisms include opposing slanted surfaces provided on the upper guide sub-part 51 d and on the upper slide-contact part 58 d, and opposing slanted surfaces on the lower guide sub-part 51 c and the lower slide-contact part 58 d, so that each pair of slanted surfaces are kept in elastic contact by the turning moment applied by the spring member. Consequently, the upper guide sub-part 51 d having a slanted surface and the upper slide-contact part 58 d, and the lower guide sub-part 51 c and the lower slide-contact part 58 c respectively abut with each other while pressed along each slanted surface. Therefore, the movable member 58 is prevented from having a vertical backlash by the upper guide sub-part 51 d and the lower guide sub-part 51 c. In addition, the movable member 58 is interposed between the upper guide sub-part 51 d and the lower guide sub-part 51 c so that a horizontal (width direction) backlash is also prevented.

[0122] The spring member is composed of the first spring member 61 a for biasing the operation shaft 57 so as to be restored from movement thereof, and the second spring member 61 b for biasing the movable member 58 so as to be restored from movement thereof, in which the second spring member 61 b is formed of one coil spring for pushing the movable member 58 in a restoring direction at a position offset from the central axis. To generate the turning moment M in the movable member 58, the second spring member 61 b composed of a coil spring which is separately provided from the spring member having a coil spring for restoring the movement of the operation shaft 57. Therefore, it is possible to obtain a desirable and simple structure providing better mounting workability and low cost productivity.

[0123] The prolonged arm parts 57 c, each extending toward outer ends along the width direction of the movable member 58 and perpendicular to the axial direction, are provided on the operation shaft 57 at an end contacting the movable member 58, each prolonged arm part 57 c in contact with the first spring members 61 a, such that a pair of the first spring members 61 a are provided at the outer ends along the width direction of the movable member 58 so as to oppose each other. Thereby, the pressing forces for pressing the operation shaft 57 maintain a good balance. In addition, because the spring member 61 for restoring the movable member 58 from its movement is composed of a separate second spring member 61 b, restoring force applied to the contact portion of the operation shaft 57 and the movable member 58 may be dispersed, thus obtaining a more desirable operation touch. 

What is claimed is:
 1. A linear operation type electric part comprising: an operation shaft linearly movable along an axial direction; a movable member abutting with one end of the operation shaft, the movable member being disposed so as to be linearly movable by the operation shaft; a spring member for biasing the movable member so as to be restored from movement thereof; a case having a guide part for guiding the movable member during the movement thereof; and detection means disposed in a lower side of the movable member and operated by the movement of the movable member, wherein the guide of the case comprises an upper guide sub-part and a lower guide sub-part for guiding sides of the movable member from above and below, respectively; the movable member comprises: a lower slide-contact part having the detection means on a lower side thereof and sliding in contact with the lower guide sub-part; and an upper slide-contact part located above and opposing to the lower slide-contact part, the upper slide-contact part sliding in contact with the upper guide sub-part; the upper and lower guide sub-parts and the upper and lower slide-contact parts form a restriction mechanism for restricting the movement of the movable member; the movable member receives from the spring member a turning moment for inclining a center line of the movable member in a width direction with respect to the axial direction, the center line extending along a front-to-back direction from a center of the movable member, thus rotating the movable member on a plane of the width direction; the rotation causes the upper and lower slide-contact part of the movable member to be pressed against and in contact with the upper and lower guide sub-parts of the case, respectively; the restriction mechanism restricts the movement of the movable member along the vertical and width directions so as to prevent a backlash of the movable member; and the movable member moves linearly while being inclined in the width direction with respect to the axial direction.
 2. The linear operation type electric part according to claim 1, wherein the restriction mechanism has a slanted surface on each of the upper and lower guide sub-parts or on each of the upper and lower slide-contact parts.
 3. The linear operation type electric part according to claim 1, wherein the restriction mechanism has a slanted surface on each of the upper guide sub-part and the upper slide-contact part or on each of the lower guide part and the lower slide-contact part.
 4. The linear operation type electric part according to claim 3, wherein the restriction mechanism comprises either a pair of the upper guide sub-part and the upper slide-contact part or on each of the lower guide sub-part and the lower slide-contact part are formed so that the slanted surfaces are capable of abutting with each other while the other pair comprises an arc-shaped surface and a flat surface abutting with the arc-shaped surface.
 5. The linear operation type electric part according to claim 1, wherein the restriction mechanism comprises first and second restriction mechanisms provided on left and right sides along the width direction interposing the axial direction of the operation shaft.
 6. The linear operation type electric part according to claim 5, wherein one of the first and second restriction mechanisms is positioned near the operation shaft while the other of the first and second restriction mechanisms is positioned farther from the operation shaft than the one of the first and second restriction mechanisms.
 7. The linear operation type electric part according to claim 1, wherein the turning moment of the movable member is generated by the spring member comprising one coil spring.
 8. The linear operation type electric part according to claim 1, wherein the turning moment of the movable member is generated by the spring member comprising two coil springs disposed on left and right sides along the width direction interposing the axial direction of the operation shaft.
 9. The linear operation type electric part according to claim 8, wherein a pressure applied to the movable member by each of the two coil springs is differentiated by differentiating a distance between a position at which each coil spring abuts with the movable member and a position at which the coil spring abuts with the case.
 10. The linear operation type electric part according to claim 8, wherein the two coil springs are disposed at positions on a line extending perpendicularly to the axial direction of the operation shaft.
 11. The linear operation type electric part according to claim 1, wherein the movable member is in elastic contact with the operation shaft due to an action of the spring member.
 12. The linear operation type electric part according to claim 1, the restriction mechanism is formed of a slanted surface on at least one of the upper guide sub-part and the upper sliding part, a flat surface on one of the lower guide sub-part and the lower sliding part, and a flat surface or at least one pair of convex portions in contact with the flat surface provided on the other of the lower guide sub-part and the lower sliding part.
 13. The linear operation type electric part according to claim 1, the restriction mechanism is formed of a slanted surface on at least one of the lower guide sub-part and the lower sliding part, a flat surface on one of the upper guide sub-part and the upper sliding part, and a flat surface or at least one pair of convex portions in contact with the flat surface provided on the other of the upper guide sub-part and the upper sliding part.
 14. The linear operation type electric part according to claim 1, wherein the restriction mechanisms comprise opposing slanted surfaces provided on the upper guide sub-part and on the upper slide-contact part, and opposing slanted surfaces on the lower guide sub-part and the lower slide-contact part, so that each pair of slanted surfaces are kept in elastic contact by the turning moment applied by the spring member.
 15. The linear operation type electric part according to claim 14, wherein the spring member comprises a first spring member for biasing the operation shaft so as to be restored from movement thereof, and a second spring member for biasing the movable member so as to be restored from movement thereof, wherein the second spring member is formed of one coil spring for pushing the movable member in a restoring direction at a position offset from the central axis.
 16. The linear operation type electric part according to claim 15, wherein prolonged arm parts, each extending toward outer ends along the width direction of the movable member and perpendicular to the axial direction, are provided on the operation shaft at an end contacting the movable member, each prolonged arm part being in contact with the first spring member, such that a pair of the first springs are provided at the outer ends along the width direction of the movable member so as to oppose each other. 